ACOUSTIC SHIELD FOR NOISE REDUCTION IN WIND TURBINES
A wind blade is provided that includes a primary blade body defining a leading edge and a trailing edge and further defining a pressure side and a suction side joining along the trailing edge. The wind blade also includes a secondary blade having an aerodynamic contour defining a first surface and a second surface and coupled with the primary blade body for the purpose of shielding noise. The secondary blade body is disposed proximate to at least a portion of the trailing edge on at least one of the pressure side and the suction side of the primary blade body and may also improve overall performance of the wind blade.
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The present application relates generally to wind turbines and more particularly relates to noise attenuating systems for the reduction of noise produced during operation of wind turbine rotor blades.
During the operation of a wind blade with an airfoil-shaped section, the fluid, for example air, flows along the airfoil-shape forming a boundary layer. Generally the boundary layer is laminar in the proximity of a leading edge of the wind blade and transitions to a turbulent state over the body of the airfoil-shaped wind blade. During operation, the wind blade generates considerable noise, which is a major constraint in utilizing the wind turbines for power production as the noise may bother people in residential areas located nearby.
One cause of the noise generated during the operation of the wind blade is the interaction of a trailing edge of the airfoil-shaped wind blade with the turbulent flow in the turbulent boundary layer. A turbulent flow includes various groups of randomly oriented turbulent eddies of various sizes and intensities that are associated with a turbulent kinetic energy. Generally, the higher the turbulent kinetic energy associated with the turbulent eddies, and the closer the turbulent eddies are to a scattering edge, the higher the noise produced. Furthermore, groups of large eddies are associated with low frequency noise and groups of small eddies are associated high frequency noise. The distribution of eddy sizes, the proximity of eddies to scattering surfaces such as an airfoil, and the response of the human ear to noise determine perceived noise levels.
There is therefore a desire for a wind blade that generates less noise during operation while maintaining the aerodynamic performance of the wind turbine.
BRIEF DESCRIPTIONIn accordance with an embodiment of the invention, a wind blade is provided. The wind blade includes a primary blade body defining a leading edge and a trailing edge and further defining a pressure side and a suction side joining along the trailing edge. The wind blade also includes a secondary blade having an aerodynamic contour defining a first surface and a second surface and coupled with the primary blade body for shielding noise, wherein the secondary blade body is disposed proximate to at least a portion of the trailing edge on at least one of the pressure side and the suction side of the primary blade body.
In accordance with an embodiment of the invention, a method of reducing noise in a wind turbine is provided. The method includes providing a primary blade body defining a leading edge and a trailing edge and further defining a pressure side and a suction side joining along the trailing edge. The method also includes disposing a secondary blade body having an aerodynamic contour proximate to one of at least a portion of the trailing edge and the leading edge on at least one of the pressure side and the suction side of the primary blade body.
In accordance with an embodiment of the invention, a wind turbine is provided. The wind turbine includes multiple wind blades, wherein each of the blades comprises a primary blade body defining a leading edge and a trailing edge and further defining a pressure side and a suction side joining along the trailing edge. Further, each of the blades includes a secondary blade body having an aerodynamic contour defining a first surface and a second surface and coupled with the primary blade body for shielding noise, wherein the secondary blade body is disposed proximate to one of at least a portion of the trailing edge and the leading edge on at least one of the pressure side and the suction side of the primary blade body.
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
When introducing elements of various embodiments of the present invention, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. The terms “secondary blade body” and “acoustic shield” are used interchangeably and intended to mean the same element in the present invention. Any examples of operating parameters are not exclusive of other parameters of the disclosed embodiments.
Furthermore, the first surface 42 of the secondary blade body 40 (or acoustic shield) is coupled with the primary blade body 29 using adhesive via a plurality of stents. Also, the coupling of the secondary blade body 40 (or acoustic shield) involves local reinforcement of the skins belonging to the primary and secondary blade bodies. In one embodiment, the secondary blade body may be configured to be retrofitted with the primary blade body 29. The secondary blade body or the acoustic shield 40 can be attached to the primary blade via short rod like structures made of metal, fiberglass or other material that can be glued to the structure or skin of the primary blade.
As shown in this embodiment in
In yet another embodiment, the secondary blade body 62 (or acoustic shield) may be disposed on a pressure side 30 towards a leading edge 34. It is to be noted that the material of the secondary blade body and the coupling of the primary blade body with the secondary blade body as discussed in embodiments of
Advantageously, the present invention enables reduced noise emission from the wind blades having acoustic shields, thereby, allowing more turbine installation in a given site and consequently increasing the Annual Energy Production (AEP) of the site. This benefit is gained with a negligible change in blade overall performance, and a negligible additional structural loading on the wind turbine. The acoustic shield can be used to significantly reduce trailing edge noise, but also the noise generated at the leading edge due to turbulent inflow. Careful aerodynamic design of the shield can lead to performance improvements of the blade aerodynamic efficiency through a reduction of tip losses. This can enable higher tip speeds and thus lead to greater torque and AEP. It can be retrofitted, leading to a significant noise reduction with a minimal downtime of the wind turbine.
Furthermore, the skilled artisan will recognize the interchangeability of various features from different embodiments. Similarly, the various method steps and features described, as well as other known equivalents for each such methods and feature, can be mixed and matched by one of ordinary skill in this art to construct additional systems and techniques in accordance with principles of this disclosure. Of course, it is to be understood that not necessarily all such objects or advantages described above may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the systems and techniques described herein may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.
While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.
Claims
1. A wind blade comprising:
- a primary blade body defining a leading edge and a trailing edge and further defining a pressure side and a suction side joining along the trailing edge; and
- a secondary blade body having an aerodynamic contour defining a first surface and a second surface and coupled with the primary blade body for shielding noise, wherein the secondary blade body is disposed proximate to at least a portion of the trailing edge on at least one of the pressure side and the suction side of the primary blade body for improving overall performance of the wind blade.
2. The wind blade of claim 1, wherein the secondary blade body is disposed on the primary blade body proximate to a tip region of the wind blade such that the secondary blade body acts as an acoustic shield.
3. The wind blade of claim 2, wherein the secondary blade body is disposed within about one-third of an outer region of the primary blade body towards the tip region of the wind blade.
4. The wind blade of claim 3, wherein the tip region of the wind blade is faired with the secondary blade body allowing for recovery of a tip vortex with high blade efficiency.
5. The wind blade of claim 1, wherein the first surface of the secondary blade body is coupled with the primary blade body on the suction side.
6. The wind blade of claim 1, wherein the second surface of the secondary blade body is coupled with primary blade body on the pressure side.
7. The wind blade of claim 1, wherein the secondary blade body is coupled with the primary blade body using adhesive via a plurality of stents.
8. The wind blade of claim 1, wherein the secondary blade body is configured to be retrofitted with the primary blade body.
9. The wind blade of claim 1, wherein the secondary blade body comprises a thin shell structure.
10. The wind blade of claim 1, wherein the secondary blade body comprises a material selected from a group consisting of metals or composite materials comprising fiber glass, carbon fiber and Kevlar.
11. The wind blade of claim 1, wherein the secondary blade body comprises a thickness to chord ratio in a range of about 0.03 to 0.08.
12. The wind blade of claim 1, wherein the secondary blade body comprises a chord-wise thickness in a range of about 5% to 15% of the primary blade body.
13. A method of reducing noise in a wind turbine, the method comprising:
- providing a primary blade body defining a leading edge and a trailing edge and further defining a pressure side and a suction side joining along the trailing edge;
- disposing a secondary blade body having an aerodynamic contour proximate to one of at least a portion of the trailing edge and the leading edge on at least one of the pressure side and the suction side of the primary blade body.
14. The method of claim 13, further comprising disposing the secondary blade body having a first surface and a second surface on the primary blade body by gluing via a pluralty of stents.
15. The method of claim 13, further comprising disposing the secondary blade body within one-third of an outer region of the primary blade body towards the tip region of the wind blade.
16. The method of claim 15, further comprising fairing the secondary blade body with the tip region of the wind blade for allowing a smooth laminar flow of wind over the wind blade.
17. A wind turbine comprising:
- a plurality of wind blades, wherein each of the blade comprises:
- a primary blade body defining a leading edge and a trailing edge and further defining a pressure side and a suction side joining along the trailing edge; and
- a secondary blade body having an aerodynamic contour defining a first surface and a second surface and coupled with the primary blade body for shielding noise, wherein the secondary blade body is disposed proximate to one of at least a portion of the trailing edge and the leading edge on at least one of the pressure side and the suction side of the primary blade body.
18. The wind turbine of claim 17, wherein the secondary blade body is coupled with the primary blade body on the suction side or the pressure side.
19. The wind turbine of claim 17, wherein the secondary blade body is coupled proximate to at least a portion of the trailing edge on the suction side of the primary blade body such that an edge of the secondary blade body is aft of the trailing edge.
20. The wind turbine of claim 17, wherein the secondary blade body is disposed within one-third of an outer region of the primary blade body towards a tip region of the wind blade.
Type: Application
Filed: Mar 28, 2013
Publication Date: Oct 2, 2014
Patent Grant number: 9677537
Applicant: General Electric Company (Schenectady, NY)
Inventors: Lorenz Edwin Drack (Munich), Thierry Pascal Maeder (Munich), Gowri Jaganathan Sengundermudaliar (Bangalore), Karthickprabu Vijayakumar (Bangalore)
Application Number: 13/852,562
International Classification: F03D 1/06 (20060101); F03D 1/00 (20060101);